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991.
As a special substance between isolated molecules and condensed phase, clusters have drawn more and more attention by theoreticians and experimentalists. The protonated rare gas cluster is one kind of simplest clusters, which can be looked on as the simplest solution composed of the simplest solute, proton, and the simplest solvent, rare gas. The study on such a system can help us to know more about the complex condensed matter. However, the information for the molecular properties of protonat… 相似文献
992.
Two different spectrofluorimetric methods for the determination of piroxicam (PX) in serum are presented and discussed. One of them is based on the use of three-way fluorescence data and multivariate calibration performed with parallel factor analysis (PARAFAC) and self-weighted alternating trilinear decomposition (SWATLD). This methodology exploits the so-called second-order advantage of the three-way data, allowing to obtain the concentration of the studied analyte in the presence of any number of uncalibrated (serum) components. The method was developed following two different procedures: internal standard addition and external calibration with standard solutions, which were compared and discussed. The second approach investigated is based on the combination of solid-phase extraction (SPE) and room temperature fluorimetry. Both methods here presented yield satisfactory results. The concentration range in which PX could be determined in serum was 1–10 μg ml−1. The limits of quantification for the experimental solutions using the chemometric approach were 0.09 μg ml−1 for the standard addition mode and 0.12 μg ml−1 using external calibration (both for PARAFAC and SWATLD algorithms). In the solid-surface fluorimetric method, the calibration graph was linear up to 0.22 μg ml−1 and the limit of quantification was 0.02 μg ml−1. 相似文献
993.
Yong Yang Su Zhi Ming Li Hong Bo Dong Guo Qing Zhou Li Hua Zhai Jiang Xu 《International journal of environmental analytical chemistry》2013,93(5):473-483
An ambient aerosol concentration enrichment system coupled with ICP-MS for real-time monitoring of airborne radioactive particles is now under development. ICP-MS is very sensitive to sample introduction conditions, so it is necessary to develop an easy-use calibration method for on-line quantitative analysis in field application. In this paper, a calibration method using standard solution instead of monodisperse particles was established and validated preliminarily. First of all, four parameters for the method were determined experimentally, including: uptake flow rate and nebulisation efficiency of the Microconcentric nebuliser, nebulisation/transport efficiency of Aridus Desolvating Sample Introduction System, and Relative Sensitivity Factor between 159?Tb and 174?Yb. Then, monodisperse terbium nitrate particles were generated by a commercial Vibrating Orifice Aerosol Generator. Continuous aerosols of ytterbium nitrate droplets were nebulised from standard solution. They were mixed together, desolvated through the membrane dryer and introduced into ICP-MS for on-line analysis of terbium nitrate particles. The air sampled from nuclear environment was also introduced into ICP-MS to investigate the effect of flow rate on instrument responses. Finally, atom numbers of 159?Tb in discrete terbium nitrate particles were determined using the calibration method and compared to the calculated value. Results show that when air flow rate increase from 10?mL?min?1 to 100?mL?min?1, the ratio of 159?Tb ion count to 174?Yb ion intensity keeps constant although instrument sensitivity decreases by a factor of 25. The relative standard deviation of 159?Tb atom number measured is better than 18%. The discrepancy with the calculated value could be attributed to the over-estimation of atom number in the particles generated by VOAG because there was some liquid leakage in the VOAG. 相似文献
994.
Roger Kerouel Alain Aminot 《International journal of environmental analytical chemistry》2013,93(1-4):83-85
Abstract Since plastics are suspected to adsorb orthophosphate, disposable-tip pipettes have been checked to determine their ability to be used in orthophosphate calibration. No adsorption has been detected through an experiment of standard preparation with and without changing the pipette tip. That is, the pipettes appear to be convenient for orthophosphate calibration. 相似文献
995.
采用高温固相法制备了Sr_3Y(BO_3)_3:xTm~(3+),yDy~(3+)荧光粉,并通过XRD、SEM和荧光光谱仪对样品的物相、微观形貌、发光性能、能量传递机制和CIE色坐标进行了分析。结果表明:Sr_3Y(BO_3)_3:xTm~(3+)荧光粉在监测波长为359 nm时发射蓝光,Tm~(3+)的浓度淬灭点为x=0.08;在Sr_3Y(BO_3)_3:0.08Tm~(3+),yDy~(3+)荧光粉中,随着Dy~(3+)掺杂浓度的增加,Tm~(3+)的发光强度降低而Dy~(3+)发光强度却先增加后降低,Dy~(3+)的浓度淬灭点为y=0.1;通过改变Dy~(3+)掺杂浓度或改变激发光的波长,均可实现发射光的颜色可调;在Tm~(3+)-Dy~(3+)离子之间存在能量传递。当Dy~(3+)掺杂浓度(物质的量分数)为0.15时能量传递效率达75.14%,能量传递机制为电偶极-电偶极相互作用。 相似文献
996.
Nobumasa Chaki Dr. Satoru Muramatsu Yuji Iida Seiya Kenjo Prof. Dr. Yoshiya Inokuchi Prof. Dr. Toshifumi Iimori Prof. Dr. Takayuki Ebata 《Chemphyschem》2019,20(8):996-1000
The S1 electronic state of 7,7,8,8-Tetracyanoquinodimethane (TCNQ) has been investigated by laser induced fluorescence (LIF), dispersed fluorescence (DF) spectroscopy, and lifetime measurements under jet-cooled conditions in the gas-phase. The LIF spectrum showed a weak origin band at 412.13 nm (24262 cm−1) with prominent progression and combination bands involving vibrations of 327, 1098, and 2430 cm−1. In addition, very strong bands appeared at ∼363.6 nm (3300 cm−1 above the origin). Both the LIF and DF spectra indicate considerable geometric change in the S1 state. The fluorescence lifetime of S1 at zero-point level was obtained to be 220 ns. This lifetime is 40 times longer than the radiative lifetime estimated from the S1−S0 oscillator strength. Furthermore, the lifetimes of the vibronic bands exhibited drastic energy dependence, indicating a strong mixing with the triplet (T1) or intramolecular charge-transfer (CT) state. This study is thought to disclose intrinsic nature of TCNQ, which has been well known as a component of organic semiconductors and a versatile p-type dopant. 相似文献
997.
Jia-Lin Chang Jung-Hang Hsieh Yun-Jhu Huang Chiing-Chang Chen Mu-Fong Chang 《International journal of quantum chemistry》2019,119(8):e25866
We calculated the equilibrium geometries and harmonic vibrational frequencies of the ground state and five cationic states of dichloroketene using (TD-)B3LYP, PBE0, and M06/M06-2X approaches. The photoelectron spectra of dichloroketene were simulated by computing Franck-Condon factors. The ionization energies were computed using the CCSD(T) approach with extrapolation to the complete basis set (CBS) limit. We propose two new CBS energy formulas (E = ECBS + Aexp(-x) + B/(x−1) n, n = 2 or 3) and compare the performance of different CBS approaches. A new ionic state of dichloroketene belonging to the Cs point group is reported. This state is identified as the first excited state of Cl2CCO+ having a double-well potential-energy curve along the CCO bending mode with a barrier height of 1.335 eV. The simulated photoelectron spectra are in agreement with the experiment. The vertical ionization energies calculated via spectral simulation are more accurate compared with those obtained at the ground-state structure. Among the CBS formulas used, the proposed ansatz with n = 2 performs best, with a mean absolute error of 0.021 and 0.012 eV for the adiabatic and vertical ionization energies, respectively. 相似文献
998.
Ronald Hesse Carsten Bundesmann Reinhard Denecke 《Surface and interface analysis : SIA》2019,51(13):1342-1350
The improvement of the software UNIFIT 2020 from an analysis processing software for photoelectron spectroscopy (XPS) only to a powerful tool for XPS, Auger electron spectroscopy (AES), X-ray absorption spectroscopy (XAS), and Raman spectroscopy requires new additional programme routines. Particularly, the implementation of the analysis of Raman spectra needs a well-working automatic spike correction. The application of the modified discrete Laplace operator method allows for a perfect localization and correction of the spikes and finally a successful peak fit of the spectra. The theoretical basis is described. Test spectra allow for the evaluation of the presented method. A comparison of the original and spike-corrected real measurements demonstrates the high quality of the method used. 相似文献
999.
在体积排阻色谱(SEC)法测定胸腺肽分子量校准曲线过程中,流动相中乙腈的比例对核糖核酸酶A、人胰岛素、胸腺肽α1和生长激素释放抑制因子4种蛋白的保留时间有重要影响,进而影响校准曲线的线性关系。当乙腈比例为75%时,胸腺肽分子量校准曲线线性最好,此时分子量校准方程为y=-3.138 6x+21.724,线性相关系数r2=0.988 5。4种蛋白的理论塔板数在45 783~63 345之间,拖尾因子在0.96~1.18之间,分离度在3.52~8.82之间。SEC法测定胸腺肽分子量校准曲线的液相色谱条件对4种蛋白的分离效果优异,分子量校准曲线线性良好,可用于胸腺肽制剂中高分子量物质的检测。 相似文献
1000.